The ASF is roughly the same regardless of location, but the mass transfer (of copper ions) is going to be different due to concentration gradients being different, and that depends on bulk solution concentration, agitation, copper patterns on the board, hole geometry and probably a few other things to lesser degree. The PTH in the middle of a ground plane will plate slower than a isolated one, due to lower Cu++ concentrations in the area right around the ground plane hole. I suppose what you are really asking is "how does one calculate the plating rate in this hole or that hole?" I don't think there's a simple formula, though I understand some CAM software (we don't have) does look at copper distribution and recommend adding thief areas to boards that need it. One can reduce the plating variation in acid Cu by operating at the low end on CuSO4 conc. and the high end on H2SO4 conc., maximizing agitation, evening out anode distribution, and increasing anode-to-panel distance. But knowing all that hasn't helped me reduce copper thickness variation much, so I'll be looking for better answers along with you! > ---------- > From: Robert Jordan > Sent: Tuesday, October 19, 1999 7:45 AM > Subject: ASF info...Super Plater > > Hello, > Once again another question drawing in the vast talent and experience of > Technet. Is there a way to calculate the ASF inside a through hole in a > printed circuit board during the electroplate copper process? Is that ASF > different if the pth is in the middle of a ground plane vs. an isolated > area? If no formula exists please bend my ear with your opinion. > > Thanks, > Bob Jordan > ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################